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Re: Prehistoric Times (Tanystropheus, rigor mortis)



*** Here's another alternative theory I don't think has been mentioned as
yet.  Is it possible that if these animals died somewhere out in the water,
that when they eventually sunk to the bottom, head and neck oriented
downwards during the descent, that upon making contact with the sediment at
the bottom, the body just collapses over top of the neck and head, creating
this unusual "posture"?  So that this might be an artefact of the
post-mortem / burial process, rather than being related to rigor?

I'm suggesting that the body collapsed on top of the neck and head Tracy,
because in your skeletal drawing, a number of post cranial elements (right
humerus, right femur, right tib/fib AND left tib/fib-metatarsals which
appear to be articulated to the left femur and therefore an intact and
undisturbed limb when buried) seem to ALL be overlaying the cervical series
( implying the neck lay beneath the body), which differs from your life
restoration, in which you show the neck passing behind the right forelimb(as
in your skeletal drawing), but forward and ahead off the lower extremities.
It looks to me like when this animal was sinking towards the bottom its
neck, body and tail formed a graceful offset loop, like if you snipped a
section out of a wire coil. Upon reaching the bottom, I think the neck made
contact first and the most flexible articulation where the proximal most
cervical attaches the neck to the body, allowed the "weight" of the body to
rest, belly up, over the head and neck.

Mike S.

> Please be so patient and let me add my last (at least for today) toughts
on
> this:
>
> Without dismissing other possibilities I would recall that surely ligament
> contraction in dead animals  occurs mainly in drier areas, but rigor
mortis
> (RM), i. e. contraction of *muscles* after death, may take place in water
> as well as on land. RM happens (recalling to memory good old teachings of
> anatomy)  because death stops production of ATP which is (VERY ROUGHLY
> SPEAKING) responsable of muscle de-contraction by pushing off Calcium ions
> from muscle protein (? tropomyosine ?) receptors.
> When there is no more ATP, nothing pushes off the Calcium and muscles stay
> contracted. RM normally does not produce odd,  too contorted postures if
> the antagonist muscles are balanced, because all become contracted .
> However if  epaxial muscles were more developed,  bigger etc. than
hypaxial
> ones, it is feasible that they may induce some deformation in posture with
> their contraction.
> If the epaxial muscles in the neck of Tanystropheus were more developed
> than hypaxial ones, since these latter may have been in part replaced by
> the  rib "bundles"- that can't contract-, this may explain why we found
all
> these advanced prolacertiforms  (i. e. Tany., Macrocnemus,
> Langobardisaurus, Cosesaurus and, correct me if I'm wrong,
> Tanytrachelos)  with the neck sharply bent or even curled backwards.
> Does it sound feasible to you?
>
> Cheers
>                                                  Silvio Renesto<<
>
> Ok, I'll buy that. Sounds good to me.
>
>
>
>
> Tracy L. Ford
> P. O. Box 1171
> Poway Ca  92074
>
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